Rheumatoid arthritis (RA) is a prototypical autoimmune arthritis affecting nearly 1% of the world population and is a significant cause of worldwide disability. Though prior studies have demonstrated the appearance of RA-related autoantibodies years before the onset of clinical RA, the pattern of immunologic events preceding the development of RA remains unclear. To characterize the evolution of the autoantibody response in the preclinical phase of RA, we used a novel multiplex autoantigen array to evaluate development of the anti-citrullinated protein antibodies (ACPA) and to determine if epitope spread correlates with rise in serum cytokines and imminent onset of clinical RA. To do so, we utilized a cohort of 81 patients with clinical RA for whom stored serum was available from 1–12 years prior to disease onset. We evaluated the accumulation of ACPA subtypes over time and correlated this accumulation with elevations in serum cytokines. We then used logistic regression to identify a profile of biomarkers which predicts the imminent onset of clinical RA (defined as within 2 years of testing). We observed a time-dependent expansion of ACPA specificity with the number of ACPA subtypes. At the earliest timepoints, we found autoantibodies targeting several innate immune ligands including citrullinated histones, fibrinogen, and biglycan, thus providing insights into the earliest autoantigen targets and potential mechanisms underlying the onset and development of autoimmunity in RA. Additionally, expansion of the ACPA response strongly predicted elevations in many inflammatory cytokines including TNF-α, IL-6, IL-12p70, and IFN-γ. Thus, we observe that the preclinical phase of RA is characterized by an accumulation of multiple autoantibody specificities reflecting the process of epitope spread. Epitope expansion is closely correlated with the appearance of preclinical inflammation, and we identify a biomarker profile including autoantibodies and cytokines which predicts the imminent onset of clinical arthritis.

Objective. To evaluate levels of biomarkers in preclinical rheumatoid arthritis (RA) and to use elevated biomarkers to develop a model for the prediction of time to future diagnosis of seropositive RA.Methods. Stored samples obtained from 73 military cases with seropositive RA prior to RA diagnosis and from controls (mean 2.9 samples per case; samples collected a mean of 6.6 years prior to diagnosis) were tested for rheumatoid factor (RF) isotypes, anti-cyclic citrullinated peptide (anti-CCP) antibodies, 14 cytokines and chemokines (by bead-based assay), and C-reactive protein (CRP).Results. Preclinical positivity for anti-CCP and/or >2 RF isotypes was >96% specific for future RA. In preclinical RA, levels of the following were positive in a significantly greater proportion of RA cases versus controls: interleukin-1␣ (IL-1␣), IL-1␤, IL-6, IL-10, IL-12p40, IL-12p70, IL-15, fibroblast growth factor 2, flt-3 ligand, tumor necrosis factor ␣, interferon-␥-inducible 10-kd protein, granulocyte-macrophage colony-stimulating factor, and CRP. Also, increasing numbers of elevated cytokines/chemokines were present in cases nearer to the time of diagnosis. RA patients who were >40 years old at diagnosis had a higher proportion of samples positive for cytokines/chemokines 5-10 years prior to diagnosis than did patients who were <40 years old at diagnosis (P < 0.01). In regression modeling using only case samples positive for autoantibodies highly specific for future RA, increasing numbers of cytokines/chemokines were predictive of decreased time to diagnosis, and the predicted time to diagnosis based on cytokines/chemokines was longer in older compared with younger cases.Conclusion. Levels of autoantibodies, cytokines/ chemokines, and CRP are elevated in the preclinical period of RA development. In preclinical autoantibodypositive cases, the number of elevated cytokines/ chemokines is predictive of the time of diagnosis of future RA in an age-dependent manner.Multiple studies have demonstrated that levels of disease-related biomarkers may be elevated prior to the onset of symptomatic rheumatoid arthritis (RA). These biomarkers include rheumatoid factor (RF) and antibodies to citrullinated protein antigens, as well as secre-

Objective To examine the relationship of Porphyromonas gingivalis to the presence of autoantibodies in individuals at risk of rheumatoid arthritis (RA). Methods Study participants included the following: 1) a cohort enriched in subjects with HLA–DR4 and 2) subjects at risk of RA by virtue of having a first‐degree relative with RA. None of the study subjects satisfied the American College of Rheumatology 1987 classification criteria for RA. Autoantibodies measured included anti–citrullinated protein antibody (ACPA; by second‐generation anti–cyclic citrullinated peptide antibody enzyme‐linked immunosorbent assay [ELISA]) and rheumatoid factor (RF; by nephelometry or ELISA for IgA, IgM, or IgG isotype). Individuals were considered autoantibody positive (n = 113) if they had ≥1 RA‐related autoantibody; individuals were further categorized as high risk (n = 38) if they had ACPA or positive findings ≥2 assays for RF. Autoantibody‐negative individuals (n = 171) served as a comparator group. Antibody to P gingivalis, P intermedia, and F nucleatum were measured. Associations of bacterial antibodies with group status were examined using logistic regression. Results Anti–P gingivalis concentrations were higher in high‐risk (P = 0.011) and autoantibody positive group (P = 0.010) than in the autoantibody negative group. There were no group differences in anti–P intermedia or anti–F nucleatum concentrations. After multivariable adjustment, anti–P gingivalis concentrations (but not anti–P intermedia or anti–F nucleatum) were significantly associated with autoantibody‐positive and high‐risk status (P < 0.05). Conclusion Immunity to P gingivalis, but not P intermedia or F nucleatum, is significantly associated with the presence of RA‐related autoantibodies in individuals at risk of RA. These results support the hypothesis that infection with P gingivalis may play a central role in the early loss of tolerance to self antigens that occurs in the pathogenesis of RA.

Objective To evaluate the presence of pulmonary abnormalities in subjects with rheumatoid arthritis (RA)-related autoantibody (Ab) positivity without inflammatory arthritis (IA). Methods 42 subjects without IA but with elevations of anti-cyclic citrullinated peptide antibodies and/or 2 or more rheumatoid factor isotypes (a profile that is 96% specific for RA), 15 Ab(−) controls and 12 patients with early established seropositive RA (<1 year duration) underwent spirometry and high-resolution computed tomographic (HRCT) lung imaging. Results The median age of Ab(+) subjects was 54 years-old, 52% were female and 38% were smokers (not significantly different than Ab(−) controls). No Ab(+) subject had IA on joint examination. On HRCT, 76% of Ab(+) subjects had airways abnormalities including bronchial wall thickening, bronchiectasis, centrilobular opacities and air trapping, compared to 33% of Ab(−) controls (p=0.005). The Ab(+) subjects had similar prevalence and type of lung abnormalities compared to patients with early RA. Two Ab(+) subjects with airways disease developed IA classifiable as articular RA ~13 months after lung evaluation. Conclusion Airways abnormalities that are consistent with inflammation are common in Ab(+) subjects without IA, and similar to airways abnormalities seen in early RA. These findings suggest that the lung may be an early site of autoimmune-related injury, and potentially a site of generation of RA-related autoimmunity. Further studies are needed to define the mechanistic role of lung inflammation in the development of RA.

Objective To examine the association of IgG galactosylation aberrancy with disease parameters in rheumatoid arthritis (RA). Methods N-glycan analysis of serum from multiple cohorts was performed. IgG N-glycan content and timing of N-glycan aberrancy relative to disease onset was compared in healthy and RA subjects. Correlations between aberrant galactosylation and disease activity were assessed in the RA cohorts. The impact of disease activity, gender, age, anti-CCP titer, disease duration, and CRP on aberrant galactosylation was determined using multivariate analysis. N-glycan content was also compared between epitope affinity purified autoantibodies and the remaining repertoire IgG in RA subjects. Results Our results confirm the aberrant galactosylation of IgG in RA (1.36 ± 0.43) compared to healthy controls (1.01 ± 0.23) (P < 0.0001). We observe a significant correlation between levels of aberrant IgG galactosylation and disease activity (Spearman rho = 0.37, p<0.0001). This correlation is higher in females [Spearman rho = 0.60 (P<0.0001)] than males [Spearman rho = 0.16 (P = 0.10)]. Further, IgG galactosylation aberrancy substantially predates onset of arthritis and the diagnosis of RA (3.5 years) and resides selectively in the anti-citrullinated peptide autoantibody fraction. Conclusions Our findings identify aberrant IgG galactosylation as a dysregulated component of the humoral immune response in RA that begins prior to disease onset, that associates with disease activity in a gender specific manner, and that resides preferentially in autoantibodies.